Some vehicles have a system, which captures an image of a vehicle's outside view with an onboard camera and displays the captured image on a monitor of a vehicle navigation apparatus to assist a driver at the time of checking an area around the vehicle. The onboard camera is often placed at the outside of the vehicle, so that foreign objects, such as rain droplets, mud, dirt, will be likely adhered to and deposited on a front side of the onboard camera where a lens of the onboard camera is located. An image of these deposits may possibly be present in the captured image of the vehicle's outside view, which is captured with the onboard camera, to interfere with the capturing of the clear image of the vehicle's outside view. In view of the above disadvantage, for example, JP2004-182080A teaches a washer system. In this washer system, a branching portion, which includes a valve therein, is installed between a pump, which pumps washer fluid, and a nozzle, which sprays the washer fluid over a window glass. The washer fluid, which is supplied from the branching portion to the camera nozzle, is sprayed over the onboard camera to remove the deposits from the onboard camera.
A size of a subject surface area of the onboard camera (washing subject to be washed) is smaller than that of a subject surface area of the window glass (washing subject to be washed), and a flow quantity of the washer fluid required for the washing of the subject surface area differs between the window glass and the onboard camera. In the case of the above washer system where the supply destination of the washer fluid is simply switched between the onboard camera and the window glass, the same quantity of the washer fluid, which is the same as the quantity of the washer fluid set to be supplied to the window glass, is supplied to the front side of the onboard camera. Therefore, the washer fluid may be excessively supplied to the front side of the onboard camera to cause wasting of the washer fluid and heavy scattering of the washer fluid.